1. Technical Field
The following principles of the present invention relate to data transmission. More particularly, they relate to the transmission of simulcast data over a variable bandwidth channel.
2. Description of Related Art
Content services are provided by a spectrum of different suppliers. For example, residential digital video services may include digital television, Video on Demand (VOD), Internet video streaming, etc., each service typically providing audio-video data displayable at different encoded levels.
Content data is transmitted in a bitstream, or a continuous sequence of binary bits used to digitally represent compressed multimedia, e.g., video, audio, data. The bitstream is transmitted over a transmission channel. When content data is sent as a continuous bitstream, a client device buffers this stream and offers a real time playback of the same.
Mobile broadcast networks are challenging environments in which to deliver audio/video content. The bandwidth available over a connection at any particular instant varies with both time and location. This variation in bandwidth causes entire packets containing substantial audio/video content to be lost. In addition, the latency through the network, causing the video that is ultimately displayed to ‘jitter’ or lose clarity at the client. These factors may be tolerable for file transfer traffic where jitter does not matter since high level protocols correct for errors and losses.
In streaming real time live content live broadcast networks, methods already exist where transmission of audio-video content varies as a function of available network bandwidth. Depending on the bandwidth available, the head end or transmitter side of the service is able to either buffer data to send them at a different time or at real time, using an encoder to vary the content stream's compression parameters so that it can be transmitted at current available bandwidth.
Operators providing live televised services, stream in real-time, a lower quality version of a televised broadcast feed to its mobile customers. For example mobile operators like Verizon and Sprint provide live TV services, e.g., VCast Live TV, MobiTV, etc., at a reduced resolution and bitrates to mobile handsets using their services.